Question

The oxidation number of hydrogen varies from:
A.-1 to +1
B.0 to +1
C.-1 to 0
D.0 to +2

Answer 1

Oxidation number in simple words is the number that is allocated to the elements in a chemical composition. It is the count of electrons that atoms in a molecule can share, lose or gain while forming the chemical bonds with other atoms of a different element.

Complete step by step answer:

Oxidation number is also known as oxidation state. However, these terms can further have a different meaning depending upon whether we are considering the electronegativity of the atoms or not. Basically, the oxidation number helps us to describe the transfer of electrons. It is defined as the charge that an atom appears to have on forming ionic bonds with other heteroatoms. Basically, an atom having higher electronegativity is given a negative oxidation state.
Now, oxidation state or oxidation number of an atom or ion is assigned by:
1.Summing up the constant oxidation state of other atoms or molecules or ions that are bonded to it.
2.Equating the total oxidation state of a molecule or ion to the total charge of the molecule or ion.
Now, In case of hydrogen, as we know that it has electronic configuration as $1{s^1}$ , so it can act as an electron acceptor to complete its outer orbital as well as it can act as an electron donor to donate its outermost electron to gain stability. Moreover, in case of hydrides such as NaH, H occurs in -1 state whereas in acids and oxides, it occurs in +1 state. Therefore, its oxidation state varies from -1 to +1.

Hence, option A is correct.

Note: If the atoms are occurring more than once in a molecule, and if they are identically bonded, then there is no difference between them and all the atoms will have the same oxidation numbers. Moreover, the oxidation number/state is also used to determine the changes that occur in redox reactions.